Sulfides of higher fatty acids



United States Patent 3,400,139 SULFIDES OF HIGHER FATTY ACIDS George M. Calhoun, Cleveland, Ohio, assignor to Shell Oil Company, New York, N.Y., a corporation of Delaware No Drawing. Original application July 3, 1959, Ser. No. 824,796, now Patent No. 3,189,547, dated June 15, 1965. Divided and this application Feb. 3, 1965, Ser. No. 430,197

8 Claims. (Cl. 260-399) ABSTRACT OF THE DISCLOSURE Novel oil soluble dithioethers of an ester of a diol, such as polyethylene glycol and 2,2-thiodiethanol, and a fatty acid such as oleic acid are excellent lubricating oil additives.

This patent application is a division of copending patent application, Ser. No. 824,796, now US. Patent 3,189,547, issued June 15, 1965, filed July 3, 1959.

The invention relates to a new and novel class of oilsoluble complex polythioether-ester compounds.

The oil-soluble compounds of the present invention are particularly useful as improving agents for lubricating oil compositions and are obtained by reacting (a) esters of a long chain unsaturated fatty acide, RCOOH, where R is 18 or more carbon atoms, and polyoxyalkylene diols or their thio derivatives having the formula where R' and R" are the same or dilferent akyl radicals or from 2 to 8, preferably 2 to 3 carbon atoms, X is oxygen or sulfur and x and y are integers of at least 1, preferably 1 to 6 with (b) mercapto compounds such as a mercapto acid, alcohol, ether or ester so that the end product has at least 1 and preferably 2 thioether radicals I S(CH2 n Z where Z is -OR" or COOR"' andthe R' is hydrogen or a C alkyl radical and n is an integer of from 1 to 4, preferably 1. The maximum number of s(oH2/ Z units in the final compound depends on the degree of unsaturation of the intermediate ether-ester. The unsaturated fatty acid ester of the polyoxyalkylene glycol may be represented by the formula and the thioether thereof by the formula Compounds of the present invention are prepared by reacting the ether-ester with a mercapto compound such as mercapto aliphatic carboxylic acids, e.g., mercaptoacetic acid, mercaptopropionic acid, mercaptobutyric acid, or mercapto-alkanols such as Z-mercaptoethanol, 2- and 3-mercaptopropanol, 2-, 3-, and 4-Inercaptobuta1nol or ethers of said mercaptoalcohols such as methyl or octyl 2- mercaptoethanyl or mercapto esters, e.g., ethyl mercaptoacetate or ethyl mercaptobuty ate, and mixtures thereof.

The additives can be prepared by the methods described by Koenig et al. JACS 79,362 (1957) or Fitzgerald Jr. Org. Chem. 22,197 (1957) and preferably at low temperatures, from room temperature to about 50 C., in the presence of a free radical catalyst such as azo or peroxide catalysts or ultraviolet light and a nonreactive solvent such as benzene, toluene, xylene, or the like. Suitable initiators include various free radical-yielding, heterocyclic and alicyclic peroxides, such as diethyl peroxide, tertiary butyl hydroperoxide, dibenzoyl peroxide, ditertbutyl peroxide, dimethylthienyl peroxide, dicyclohexyl peroxide, dilauroyl peroxide and urea peroxide. These are mentioned by way of non-limiting examples of suitable organic peroxides. Other initiating compounds known include emulsion redox systems, such as a mixture of sodium bisulfite and persulfate, ammonium persulfate, alkali metal perborates, azo compounds, such as alpha, alpha-azodiisobutyronitrile, etc' The following examples illustrate the preparation of suitable additives for use in accordance with the present invention.

EXAMPLE I About 600 grams of diethylene glycol dioleate and 223.5 grams of mercaptoacetic acid were mixed in a flask at 20-25 C. About 240 drops (30 drops at a time) of t-butyl hydroperoxide were added over a period of 2 hours and the temperature was kept at about 37 C. The reaction mixture was diluted with 2 volumes of diethyl ether, washed with 12 lite-rs of water to pH 4, dried over Na SO filtered and the solvent stripped at C. and 2 mm. pressure. The final product was a mixture of the 9- and the 10car-boxymethylrnercaptostearate diesters of diethylene glycol.

EXAMPLE II About 600 grams of triethylene glycol dioleate and 223.5 grams of mercaptoacetic acid were mixed in a fiask at 20-25 C. About 240 (30 drops at a time) of t-butyl hydroperoxide were added over a period of 2 hours and the temperature was kept at about 37 C. The reaction mixture was diluted with 2 volumes of diethyl ether, washed with 12 liters of water to pH 4, dried over Na SO filtered and the solvent stripped at 155 C. and 2 mm. pressure. The final product was a mixture of the 9- and 10-carboxymethylmercaptostearate diesters of triethylene glycol.

EXAMPLE III About 600 grams of diethylene glycol in ricinoleate and 223.5 grams of mercaptoacetic acid were mixed in a flask of 20-25 C. About 240 drops (30 drops at a time) of t-butyl hydroperoxide were added over a period of 2 hours and the temperature was kept at about 37 C. The reaction mixture was diluted with 2 volumes of diethyl ether, washed with 12 liters of water to pH 4, dried over Na SO filtered and the solvent stripped at 155 C., and 2 mm. pressure. The final product was a mixture of the 9- and 10-carboxylmethylrnercapto-12-hydroxylstearate diester of diethylene glycol.

EXAMPLE IV About 600 grams of diethylene glycol dioleate and 223.5 grams of mercaptoethanol were mixed in a flask at 20-25 C. About 240 drops (30 drops at a time) of t-butyl hydroperoxide were added over a period of 2 hours and the temperature was kept at about 37 C. The reaction mixture was diluted with 2 volumes of diethyl ether, washed with 12 liters of water to pH 4, dried over Na SO filtered and the solvent stripped at 155 C. and 12 mm. pressure. The final product was a mixture of diethylene glycol di(9-[and 10-2-hydroxyethylmercapto] -stearate) EXAMPLE V About 600 grams of 2,2-thiodiethanol dioleate and 223.5 grams of mercaptoacetic acid were mixed in a flask at 20-25 C. About 240 drops (30 drops at a time) of t-butyl hydroperoxide were added over a period of 2 hours and the temperature was kept at about 37 C. The reaction mixture was diluted with 2 volumes of diethyl ether, washed with 12 liters of water to pH 4, dried over Na SO filtered and the solvent stripped at 155 C. and 2 mm. pressure. The final product was a mixture of 2,2- thiodiethanol di(9- and 10-carboxymethylmercaptostearate).

The mercapto-modified polyether-esters are oil-soluble and can be used in lubricating oils and oil compositions in amounts of from about 0.5% to about 20%, preferably from about 1% to about 5% by weight.

Lubricating oils in which the additives of this invention can be used include one or more of a variety of synthetic oils, e.g., di-2-ethyl-hexylsebacate or copolymers of polyalkylene oxide and alkylene glycol or natural hydrocarbon oils having a viscosity range of from 50 SUS at 100 F. to 250 SUS at 210 F. (SAE viscosity number ranging from SAE 10W to SAE 90).

Suitable oils are the gas turbine lube oils having the following properties:

Grade 1010 1065 59. 4 530 Neutral Number 0. 02 0. 01 Ash None None The following compositions are illustrative of the invention, the percentages being by weight.

Composition A: Percent Example I additive 2 1010 mineral oil Essentially balance Composition B:

Example II additive 2 1010 mineral oil Essentially balance Composition C:

1 Example III additive 2 1010 mineral oil Essentially balance Composition D:

Example IV additive 2 1010 mineral oil Essentially balance Composition E:

Example 11 additive l SAE 30 mineral oil Essentially balance Composition F:

Example V additive 2 SAE 90 mineral oil Essentially balance Composition G:

Example I additive 2 Laurie acid 2 SAE 90 mineral oil Essentially balance Composition H:

Example I additive Polyethylene-propyleneglycol having a SUS at 100 F. of 660 Essentially balance Composition I:

Example I additive 2 Di-2-ethylhexylsebacate Essentially balance Compositions of this invention were evaluated for their extreme pressure properties on a spur-gear machine. The

Speed r.p.m. 3200 Oil temperature C 100 Oil flow-rate cc./sec 10 Load in increments 5 min. at each setting.

Results of the evaluations are given in Table I and for purpose of comparison, the results obtained from the use of the base oil alone and with other known extreme pressure compositions are also given.

TABLE I Composition A, B, C and E through I 1010 mineral oil plus 2% Cm alkenyl sueeinic acid.

Score load, lbs./in:

1010 mineral oil plus 2% malonic acid 2,800 1010 mineral oil plus 2% 3-hexadeeyl adiple acid 1, 400 1010 mineral oil plus 2% dodecyl-mercaptosuccinie acid 1, 400 1010 mineral oil plus 10% glycerol monooleate 1, 800 1010 mineral oil plus 2% C H OI-I (OXO process) 600 1010 mineral oil 000 The data show the outstanding enhancement of the load-carrying ability of the oil effected by the mercaptocontaining compounds of the invention, as represented by those of Compositions A through I. On the other hand, malonic acid, succinic acid, 3-hexadecyl adipic acid and C -alkenyl succinic acid as well as sulfur-containing acids outside the scope used by applicant such as dodecyl-mercapto-succinic acid, or other types of esters and alcohols such as glycerol-monooleate, lauric acid or OX0 alcohol effected only a slight improvement.

Compositions of the present invention were also tested for their corrosion and sludge resistant properties by the following methods: (1) a Timken 2126 steel bearing was immersed in a test composition and placed in an open air oven at 150 C. for hours, and at the end of the test, the bearing examined and (2) steel rods by 3") were immersed in test compositions for 21 /2 hours at 150 C. and the amount of sludge formed on the rods was noted as shown in Table II.

TABLE II Composition 1 2 Composition A No stain 0.7 mg. sludge. 1010 mineral oil plus 2% 3(2-ethy1- Badly stained 60 mg. sludge.

hexyl)adipic acid. 1010 mineral oil plus 2% 9- and 10- mg. sludge. carboxystearic acid.

wherein X is oxygen or sulfur, R" is alkylene of 2 to 4 carbon atoms, y is an integer from 1 to 3 with the provision that when X is sulfur y is 1, R is selected from the group consisting of C .alkylene, C hydroxy alkylene and C alkenylene, n is an integer from 1 to 4 and Z is a member selected from the group and consisting of OR"' wherein R' is H or alkyl of 1 to 4 carbon atoms.

2. A compound according to claim 1 wherein X is oxygen.

3. A compound according to claim 2 wherein R' is H and R is C alkylene.

4. A compound according to claim 2 wherein R' is H and R is C hydroxyalkylene.

5. A compound according to claim 1 wherein X is sulfur, R is ethylene, R' is H and R is C alkylenes.

7. A member selected from the group consisting of S. A member selected from the group consisting of and II HOCOHr-S and mixtures thereof.

References Cited UNITED STATES PATENTS Cyphers 260399 X Calhoun et a1 260--399 X Calhoun et al 260-399 X Calhoun et al 260-399 X NICHOLAS S. RIZZO, Primary Examiner.

I. H. TURNIPSEED, Assistant Examiner. 

